Power conversion devices are designed such that the devices operate highly efficiently at the rated load. The devices are generally prone to suffer a reduction in efficiency with a light load. Therefore, in order to improve the efficiency of a power conversion device including pluralities of converters and inverters in a light load mode, there is a technique described in Japanese Unexamined Patent Application Publication No. 2010-166654 (PTL 1). In PTL 1, the load factor of entire inverter/converter modules having outputs connected in parallel with each other is monitored, and the number of inverter/converter modules assigned to run is determined, intending to improve efficiency in the light load mode.